1. Field of the Invention
The present invention relates to a measuring probe prepared by immobilizing a protein on a support surface probe to detect a pathogen, a biologically active agent, a chemical substance etc.
2. Description of the Related Art
Probes prepared by immobilizing a protein that specifically interacts to a certain substance are used as measuring probes to detect various substances such as biomaterials. For such measuring probes, a protein that selectively reacts with a specific analyte substance such as enzymes and antibodies is immobilized on a surface of a support made of, e.g., glass, metals, paper or resins.
To immobilize a protein to a support, one of the sure methods is to covalently bonding a specific substituent on the support and a specific substituent of the protein, which can provide a relatively robust and stable immobilized layer.
However, previous introduction of such a substituent may be difficult due to the material of the support, or may be undesirable in view of complication of preparation steps.
Immobilization of a protein on a support other than the above covalent bonding to the support includes adsorption to the support by electrostatic force (ion binding method), adsorption by using association based on hydrophilicity/hydrophobicity (physical adsorption method) (refer to, for example, Kagaku Binran (Chemistry handbook) 5th edition, Applied Chemistry I, Chapter 13, Section 5 (Tokyo Kagaku Dojin)). The latter method is especially useful because it enables easy and effective protein adsorption to a resin material generally used as a structure material such as polystyrene.
Even when covalent bonding between the protein and the support is not carried out, cross-linking reaction between the molecules to be immobilized (protein molecules) may be carried out to aid the immobilization (hereinafter referred to as a cross-linking method). By the cross-linking method, the molecules to be immobilized are not bonded to the support but they integrally form one fixed layer, which will reduce mobility and increase adhesiveness to the support surface. Japanese Application Laid-Open No. S61-086644 discloses a production method of a sensor using an enzyme electrode where the enzyme is cross-linked to other proteins. It also discloses a two-step method where the application of a protein solution is followed by impregnation of a solution containing a cross-linking agent. Although the cross-linking method is simple in operation, there is a risk that the excess cross-linking agent may cause undesirable change in physical properties and functions. Japanese Application Laid-Open No. H02-236153 discloses optimization of the component ratio by weight of the cross-linking agent in production of a selective permeation membrane made by cross-linking a protein and a non-proteinaceous polymer.
As a similar technique, a protein is immobilized on a support with a synthetic polymer. Japanese Application Laid-Open No. H01-235579 discloses immobilization of an enzyme onto the surface of a fibrous support using a photocurable resin. Such a system is often applied to bioreactors.